SpringBoot+策略模式实现多种文件存储模式

一、策略模式

背景

针对某种业务可能存在多种实现方式；传统方式是通过传统if…else…或者switch代码判断；

弊端：

代码可读性差
扩展性差
难以维护

策略模式简介

策略模式是一种行为型模式，它将对象和行为分开，将行为定义为一个行为接口和具体行为的实现。

组成：

抽象策略类(Strategy)：策略的抽象；
具体策略类(ConcreteStrategy)：具体的策略实现，一种具体实现；
环境类(Context)：用来操作策略的上下文环境；

二、代码实现

以文件存储方式为例

抽象策略类

package com.qiangesoft.file.core;

import org.springframework.web.multipart.MultipartFile;

/**
 * 文件存储策略接口
 *
 * @author qiangesoft
 * @date 2024-01-06
 */
public interface FileStoreStrategy {

    /**
     * 存储方式
     *
     * @return
     */
    String getType();

    /**
     * 上传文件
     *
     * @param file
     * @return
     * @throws Exception
     */
    void uploadFile(MultipartFile file) throws Exception;
}

具体策略实现

本地存储

package com.qiangesoft.file.core.local;

import com.qiangesoft.file.core.FileStoreStrategy;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;
import org.springframework.web.multipart.MultipartFile;

/**
 * 文件本地存储
 *
 * @author qiangesoft
 * @date 2024-01-06
 */
@Component
@Slf4j
public class LocalStoreStrategyImpl implements FileStoreStrategy {

    @Override
    public String getType() {
        return "LOCAL";
    }

    @Override
    public void uploadFile(MultipartFile file) throws Exception {
        log.info("upload file by local");
    }
}

minio存储

package com.qiangesoft.file.core.minio;

import com.qiangesoft.file.core.FileStoreStrategy;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;
import org.springframework.web.multipart.MultipartFile;

/**
 * 文件minio对象存储
 *
 * @author qiangesoft
 * @date 2024-01-06
 */
@Component
@Slf4j
public class MinioStoreStrategyImpl implements FileStoreStrategy {

    @Override
    public String getType() {
        return "MINIO";
    }

    @Override
    public void uploadFile(MultipartFile file) throws Exception {
        log.info("upload file by minio");
    }
}

策略上下文环境

package com.qiangesoft.file.core;

import org.springframework.stereotype.Component;

import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * 文件存储策略上下文
 *
 * @author qiangesoft
 * @date 2024-01-06
 */
@Component
public class FileStoreStrategyContext {

    /**
     * 策略实现类上下文
     */
    private final Map<String, FileStoreStrategy> strategyMap = new ConcurrentHashMap<>();

    /**
     * 利用Spring的发现机制，将实现了FileStoreStrategy的类都放到strategyMap里面
     */
    public FileStoreStrategyContext(List<FileStoreStrategy> fileStoreStrategyList) {
        for (FileStoreStrategy strategy : fileStoreStrategyList) {
            String type = strategy.getType();
            if (this.strategyMap.containsKey(type)) {
                throw new RuntimeException(String.format("Strategy [%s] is repeat!", type));
            }
            this.strategyMap.put(type, strategy);
        }
    }

    /**
     * 获取具体的策略实现类
     *
     * @param storeType
     * @return
     */
    public FileStoreStrategy getStrategy(String storeType) {
        FileStoreStrategy strategy = strategyMap.get(storeType);
        if (strategy == null) {
            throw new RuntimeException(String.format("Strategy [%s] is not found!", storeType));
        }
        return strategy;
    }
}

调用

package com.qiangesoft.file.demo;

import com.qiangesoft.file.core.FileStoreStrategy;
import com.qiangesoft.file.core.FileStoreStrategyContext;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * Demo
 *
 * @author qiangesoft
 * @date 2024-01-08
 */
@RestController
@RequestMapping("/demo")
public class DemoController {

    @Autowired
    private FileStoreStrategyContext fileStoreStrategyContext;

    @GetMapping("/upload")
    public String upload(String type) throws Exception {
        FileStoreStrategy fileStoreStrategy = fileStoreStrategyContext.getStrategy(type);
        fileStoreStrategy.uploadFile(null);
        return fileStoreStrategy.getType();
    }

}